This invention relates in general to drum support apparatus and more specifically to a drum supporting hub, a drum assembly containing the hub and method for fabricating the drum assembly.
A photoreceptor conventionally utilized for copiers and printers comprises a hollow electrically conductive cylindrical drum substrate which has been dip coated with various coatings including at least one photoconductive coating comprising pigment particles dispersed in a film-forming binder. These drum type photoreceptors are supported on an electrically conductive shaft by drum supporting hubs. The hubs are usually constructed of plastic material and have a hole through their center into which a supporting axle shaft is inserted. Since hubs are usually constructed of electrically insulating plastic material, an electrical grounding means comprising a flexible spring steel metal strip is secured to the hub and positioned to contact both the electrically conductive axle shaft and the electrically conductive metal substrate of the photoreceptor drum. One type of grounding means is illustrated in U.S. Pat. No. 4,561,763. This metal ground strip is often bent out of alignment when inserted into one end of a photoreceptor drum. Such misalignment can result in the metal strip not contacting the interior of the drum or the axle or both after insertion of the hub into the end of the drum is completed. Further, coatings electrically insulating in the dark that are formed on the surface of the interior of the drum during dip coating can adversely affect electrical grounding of the drum to the electrically conductive drum axle shaft. If inadequate electrical grounding of the drum to the axle shaft is detected after the drum has been inserted into a modular replacement unit in which photoreceptor and various other subsystems such as cleaning and charging units are permanently mounted, repair of the drum is usually impossible without destruction of the module. Often the hub is secured to the end of the drum by a thermosetting resin. Recycling of used drums having glued hubs is difficult, if not impossible, because of damage to the hub or the drum or both during removal of the hub from the drum by common techniques such as by hammering. Such removal techniques damage or destroy both the drum and the hub. The use of bolts and nuts to secure hubs to drums requires time intensive activity and does not address the problem of electrically grounding a drum substrate to the drum axle shaft.
Thus, there is a continuing need for improved photoreceptors that are more reliable and facilitate recycling.